Motion picture film projector

ABSTRACT

A motion picture film projector, particularly a sound film projector, has an automatic film-threading mechanism with which threading and loop setting are effected by first dropping the film to be threaded into a loading slot formed in the casing of the projector and then moving an operating lever from a filmloading position into the operating position. As a result of such movement the threading mechanism is activated to thread the film upon the upper and lower sprockets, to form upper and lower loops and to move the lens system into position for projection. Removal of the film is effected by simply returning the operating lever to its loading position thereby freeing the film from its engagement with the components of the threading mechanism so that the film can be lifted out of the slot. The projector has driving apparatus for rewinding the film following projection.

United States Patent [191 Schwartz et a].

[ MOTION PICTURE FILM PROJECTOR Primary ExaminerSamuel S. Matthews [75]Inventors: Morris Schwartz; Conkling Amstam gg f Hayes Chedister; FrankH. Beckman, all of Atwmey Hane ax ey Plainville, Conn.

[73 l Assignee: The Kalart Company Inc., [57] ABSTRACT Plainville, Conn.A motion picture film projector, particularly a sound 22 F] d s t 131971 film projector, has an automatic film-threading mech- 1 1e ep anismwith which threading and loop setting are ef- [21] Appl. No.: 179,630fected by first dropping the film to be threaded into a loading slotformed in the casing of the projector and Related Apphcanon Data thenmoving an operating lever from a film-loading [62] DIVISION of Ser. No.842,618,.Iuly 17, 1969, Pat. No. position into the operating position ASa result of such movement the threading mechanism is activated to threadthe film upon the upper and lower sprockets, [52] US. Cl. 352/124,226/91 to form upper and lower loops and to move th: lens IIII. C].System into position for projection. Removal of the Fleld of Search iseffected returning the operating lever 352/159 226/91 to its loadingposition thereby freeing the film from its engagement with thecomponents of the threading [56] References C'ted mechanism so that thefilm can be lifted out of the UNITED STATES PATENTS slot. The projectorhas driving apparatus for rewinding 3,426,950 2/1969 Maurer 352/158 Xthe film following projection. 3,119,300 1/1964 Barogela 352/157 x3,493,297 2/1970 McKee 352/157 x 5 C aims, 17 Drawmg Flgures 3,490,8371/1970 Peirez .1 352/157 X 1,973,477 9/1934 Fritts v. 352/157 I A Q;- 020 qD L PATENIEnnm 9mm sum 1m 0 PAIENIED 91975 3.764.203

sum u [If 0 RUNNING L mme MOTION PICTURE FILM PROJECTOR This is adivisional application divided out of application Ser. No. 842,618,filed July 17, 1969 and issued as US. Pat. No. 3,609,022 on Sept. 28,1971.

The present invention relates to motion picture film projectors, eithersilent film projectors or sound film projectors, and more particularlyto a film-threading mechanism for such projectors.

BACKGROUND With projectors as they are now widely used in theaudio-visual field for teaching and training purposes and also forshowing home movies, one of the most frequently recurring problems isthe threading of the film and the removal of the film from theprojector. Operators of projectors used in the above indicated areas andrelated areas are more often than not amateurs, or at least notspecially skilled in the operation of the projector.

Many proposals have been made to simplify the threading and the removalof the film. However, even the most simplified threading mechanism asnow known still requires accurate threading of the film on sprockets andloop forming by the operator. These operations are difficult for lessexpert users of the projectors.

THE INVENTION It is a broad object of the invention to provide a noveland improved threading mechanism for a projector of the general kindabove referred to which which reduces the skill demanded of the operatorto an absolute minimum by automatically performing all requiredthreading and loop forming functions.

A more specific object of the invention is to provide a novel andimproved threading mechanism which merely requires that the operatorinserts a suitable length of film into a loading slot and then shifts anoperating lever from a loading position to an operating position, andwhich permits an equally simple removal of the film by returning thelever into its loading position and withdrawal of the film from theloading slot by lifting the film out of the slot.

Another more specific object of the invention is to provide a novel andimproved threading mechanism which includes a loading slot that is clearof obstructions by components of the threading mechanism so that thefilm can be inserted into the loading slot by simply dropping the filminto the same without particular care on the part of the operator.

Still another object of the invention is to provide a novel and improvedthreading mechanism which automatically restores the loops in the filmwhen due to a faulty film, for instance a film having torn sprocketholes, the film tightens during operation between the upper and lowersprockets of the projector.

A further object of the invention is to provide a novel and improvedthreading mechanism which permits, if desired, a high-speed rewindwithout compromising in any way the aforedescribed simplicity of thefilm threading and removing operations.

A still further object is to provide a novel and improved threadingmechanism which permits stopping of the film at any desired moment toinspect the frame then in the film gate of the projector.

SUMMARY OF THE INVENTION The afore pointed out objects, features andadvantages andother objects, features and advantages which will bepointed out hereinafter are obtained by providing in a suitable wall ofthe projector casing, such as the front panel, a continuous slot forloading the projector with the film to be threaded by dropping a lengthof film into the slot. The upper and lower sprockets are stationarilymounted on a fixed base plate within the projector on one side of theslot therein while threading and loop-setting components of themechanism are mounted on a plate which is slidable within the projectorwith reference to the slot and the stationarily mounted components ofthe mechanism. The movable plate is displaceable by means of anoperating lever from a loading position in which all the componentssupported on this plate are disengaged from the sprockets into anoperating position. Such movement of the movable plate causes movementof the threading and loop-setting components supported by the movableplate to effect threading of the film upon the sprockets and to form theupper and lower loops between the sprockets. Movement of the movableplate into the operating position also causes movement of the projectionlens system into the projection position. Removal of the film iseffected by returning the operating lever to the loading position,thereby freeing the film so that it can be lifted out of the slot.

In the accompanying drawing several preferred embodiments of theinvention are shown by way of illustration and not by way of limitation.

In the drawing:

FIG. 1 is a diagrammatic elevational view ofa sound film projector inits operating position;

FIG. 2 is a fragmentary elevational view of FIG. I, the front cover ofthe projector having been removed to show diagrammatically the mechanismthereof;

FIG. 3 is a section taken on line 3-3 of FIG. 2 on an enlarged scale;

FIG. 4 is a detailed elevational view of the mechanism as located abovethe optical center line of the projector, the mechanism being shown inits non-operating or loading position;

FIG. 5 is a view similar to FIG. 4, but showing the mechanism in itsoperating position except for the steps effected by releasing theoperating lever of the mechanism;

FIG. 6 is a detailed elevational view of the part of the mechanism belowthe optical center axis of the projector, the mechanism being shown inits non-operating or loading position;

FIG. 7 is a view similar to FIG. 6, but showing the mechanism in itsoperating position;

FIG. 8 is a diagrammatic elevational view of the belt drives of themechanism;

FIG. 9 is a plan view of FIG. 8 taken on line 9-9 thereof and alsoshowing part of the rewind assembly of the projector;

FIG. 10 is a fragmentary elevational view of a modification of the loopsetting assembly of the mechanism;

FIG. 11 is an elevational view of another modification of the loopsetting assembly;

FIG. 12 is an elevational simplified view of the assembly according toFIG. 11, but showing the same in another operational position;

FIG. 13 is a diagrammatic view of an assembly for stopping the film toposition a frame of the film in alignment with respect to the film gateof the projector;

FIG. 14 is a perspective detailed view of components of the assemblyaccording to FIG. 13;

FIG. 15 is a diagrammatic circuit diagram for the assembly according toFIG. 13;

FIG. 16 is a perspective view, as seen from the rear, of a rewindassembly for fast rewind; and

FIG. 17 is a circuit diagram preventing operation of the projector motorfor forward drive when the mechanism is set for loading the film.

The optical system, the sound system, and the reel mounting of theprojector should be visualized as being conventional. These and otherstandard components of the projector do not constitute part of theinvention and are hence not illustrated or described in detail.

Referring now to the figures in detail, there is shown in FIG. 1 aprojector which mounts protruding therefrom in conventional fashion asupply reel 11 and a take-up reel 12. There is also shown a focusingknob 13 and a control panel 14 mounting the usual knobs for controllingthe projection light, the motor and the sound of the projector.

The front panel of the projector further shows a continuous curved slotfor inserting a sound film 25 to be threaded. The edges of the slot arepreferably ornamentally and functionally bevelled as it is indicated at19 and 20. The slot is open and free of obstructions for inserting afilm into the slot. As will be more fully explained hereinafter, all themovable components of the projector mechanism are to the right of slot15 and clear of the same. Threading ofa film as far as the operator isconcerned is effected by simply withdrawing from the supply reel asufficient length of film to permit slipping of the film into the slot,taking care only that the film is guided over guide roller 18 associatedwith supply reel 11 and over guide roller 21 associated with take-upreel 12, and by moving an perating lever 16 from the right-hand positioninto the left-hand position shown in FIG. 1. Such movement of the leverwill automatically cause complete threading of the film, and also loopsetting, as will be more fully explained hereinafter.

Lever 16 is slidable in a slot 17 terminating at its ends in L-cutouts17a and 17b to retain the lever in its limit positions. As indicatedbefore, position 170 constitutes the loading position of the projectorand position 17b the operating position.

Referring now to FIG. 2 which shows the projector with the film threadedtherein, that is, in its position ready for operation (lever 16 is inits left-hand position), the mechanism comprises a fixed or stationaryassembly and a movable assembly.

The stationary assembly, the components of which will be describedhereinafter, is mounted on a base plate 30 and the movable assembly ismounted on a plate 31, which is slidable relative to plate 30 parallelthereto. Plate 31 is guided on plate 30 by means of guide rollers 32 and33 mounted on plate 31 and engaging guide slots 34 and 35 respectively,in plate 30. Other suitable means or additional means for guiding themovable assembly to prevent jamming thereof relative to the base platemay of course be provided but are not shown to simplify the illustrationand as not constituting an essential part of the invention.

Base plate 30 is mounted operationally fixed with reference to theoptical system of the projector, diagrammatically indicated by anenclosure 36, which should be visualized as containing among othercomponents, a lamp, appropriate lenses, a condenser or heat shield and ashutter. There is also shown a fixed rear film guide 37 to the left ofthe slot 15, a film gate 38 and a film transport claw 39, the movementsof which are conventional and diagrammatically indicated in FIG. 6. Baseplate 30 mounts to the right of the slot an upper sprocket 40, a lowersprocket 41, a sound-scanning system 42 of conventional design, an upperloop setting lever 43, a double-cam plate 441, and a bar 45 disposedbehind slot 17. The bar is an optional safety element to assure positivecontrol of the locking and the movement of lever 16 instead of merelyrelying on the configuration of slot 17 as previously described.

Slidable plate 31 mounts a front film guide 50 including a film apertureor gate, a projection lens system 51, a focusing assembly 52 (see FIG.3), an upper film guide 53, an upper loop setting member 54, lower filmguides 55 and 56, a lower loop setting member 57, idler filter rollers58 and 59 and an assembly 60 which is slidable up and down withreference to plate 31 and is actuated by lever 16 by being securedthereto.

Referring to FIG. 3, focusing knob 13 is mounted on a shaft 61lengthwise slidable in a bracket 62 which may be visualized as beingsecured to a suitable wall such as a cover wall 63 of the projector.Shaft 61 is biased by a spring 64 and terminates in a nose 61aengageable with a slot 67a of a shaft 67 mounting a pinion 66 coactingwith a rack mounted on a barrel of the projection lens system 51.

As is evident from FIG. 3, the lens system can be focused by pressing inknob 13 and turning the same. The retraction of the knob by springs 64when released avoids accidental disturbance of the set focus.

Referring now to FIGS. 4 and 5, the afore referred to up and downslidable assembly 60 comprises a plate 70 including one or more guideslots, guide slots 71a, 71b and 71c being shown. Plate 70 mounts studs72 and 73 and also operating lever 16. The slots engage studs 74a, 74band 740 mounted on plate 31 to guide plate 70 relative to plate 31. Atension spring 75 secured to stud 73 on plate 70 and .to stud 74b onplate 31 biases plate 70 and thus the entire assembly 60 upwardly. Stud74c on plate 31 is extended behind plate 70 to spindle film guide 53 onplate 31. A spring 76 on stud 74c biases guide 53 for turning inclockwise direction. An additional stud 77 on plate 70 limits theclockwise turning of guide 53 by spring 76 and causes turning of theguide in counter-clockwise direction when plate 31 and with it assembly60 are moved from the position of FIG. 4 into the position of FIG. 5, aswill be more fully described hereinafter in connection with thedescription of the Operation of the projector.

Upper loop setter 54 mounted on plate 31 is in the form of a two-armlever spindled on a post 81 on plate 31. One arm of loop setter 54mounts a film loop guiding and shaping member 82. Loop setting lever 43comprises an arm 84 spindled on a post 85 secured on plate 30 andmounting a bracket 86. The arm defines a cam surface 87 and a nose 88. Aspring 89 attached to the bracket biases lever 43 in clockwisedirection. Cam 87 cooperates with stud 72 on plate 70 and nose 88cooperates with the second arm 83 of loop setter 54, as will be morefully explained hereinafter.

All the components shown in FIGS. 4 and 5 are disposed above the opticalcenter axis 300 of the projector.

Refering now to FIGS. 6 and 7, all the components shown in these figuresare mounted below the optical center axis. Base plate 30 mounts, asstated before, the sound-scanning assembly 42, the double-cam plate 44,a post 95 and a bracket 96. Scanning assembly 42 comprises an exciterlamp 97, a sound-scanning capstan 98 spindled by a post 99, and aphotocell 100. The functional optical system between the exciter and thephotocell is omitted for clarity of illustration. It may only bementioned that the light beam from the exciter to the photocelltraverses the sound track on film 25. For this purpose, the width of thecapstan is such that the capstan will not obstruct the sound track.

Cam plate 44 defines camming surfaces 101 and 102. Post 95 spindles alower loop setting actuating member 103 comprising an arm 104, a camfollower 105, ajack 106 and a spring 107. The cam follower is spindledby a post 108 fixed to arm 104. The jack spindled at post 109 also fixedto arm 104 has an extension 110 to which one end of a spring 107 isattached; the other end of the spring is secured to bracket 96 on plate30. Cam follower 105 cooperates with cam 111 pinned to a shaft 112.Spring 107 biases actuating member 103 counter-clockwise and by means ofextension 110 also orients jack 106 rotationally on post 109. Jack 106performs a substantially back and forth reciprocating movement via camfollower 105 and arm 104 when cam 111 is rotated for a purpose whichwill be more fully explained hereinafter.

The lower part of plate 31 as shown in FIGS. 6 and 7 mountsposts115,116,117,118,119,120 and 121. Lower loop setter 57 is spindledon post 115. The loop setter comprises a crank arm 122 defining a filmguiding surface 123. This surface mounts a film guide 123a whichpreferably has a flange l23b. This film guide is the only componentwhich protrudes into slot 15, as is clearly shown in FIG. 6. 11 servesas a backstop for film when the same is dropped into the slot to preventthe film from falling into the slot too deeply and out of the reach ofthe afore and hereinafter described components of the mechanism.

The afore referred to crank arm 122 also mounts a post 124. The otherarm of the crank is attached to one end of a spring 125, the other endof which is secured to post 116. The spring is a light spring and exertsupon the crank a slight counter-clockwise bias which is limited by post117.

Film guides 55 and 56 include rollers 55a, 55b and 56a, 56brespectively, and are spindled on posts 118 and 119. The guides arebiased toward each other by springs 126 and 127 respectively. ldlermembers 58 and 59 mount rollers 130 and 131 respectively, and arespindled on posts 120 and 121 respectively. The idlers are biased towardeach other by springs 128 and 129 respectively. Rollers 130 and 131 alsoact as cam followers to coact with cams 101 and 102 of cam plate 44.Moreover, edges of idler roller arms 58 and 59 engage edges 132 and 133respectively, of guides 55 and 56 respectively, to effect outwardturning of the guides with reference to cam plate 44.

Referring now to FIGS. 8 and 9, a motor 140 of the projector drives viaa sheave 141 and a shaft 142, a belt gear 143. Shaft 142 also seatsupper sprocket 40 and a clutch half 144. The other clutch half 145 ismounted on a shaft 146, secured to or constituting part ofa belt gear147 also on shaft 146. The two clutch halves are out of engagement whenclutch half 144 is rotating in clockwise direction.

A shaft 148 which drives supply reel 11 (see FlG.9) is pinned to a beltgear 149. The shaft also drives a clutch 150 which is lengthwise movableon the shaft by means ofa spindle 151. The axial position of the clutchis controlled by a crank 152 spindled on post 153 on plate 30. Shaft 148further mounts a belt gear 154 freely rotatable on the shaft. Belt gears149 and 154 have holes 149a and 154a respectively, as shown, to receiveclutch pins 151a and 151b respectively.

A positive drive belt 155, such as a toothed belt, is guided over gears143, 149, 156 and 157. A second belt 158, also a positive drive belt,drives gears 147 and 154. Crank 152 terminates at a point at which it isengageable with post 159 on plate 31. As shown in FIG. 9, with plate 31in the position for loading, that is, in its non-operating position,crank 152 will occupy the dotted line position in which clutch pin 151bis disengaged from gear 149 and clutch pin 151a is engaged with gear154.

OPERATION OF THE PROJECTOR Threading of film 25 is effected as follows:

The threading operationbasically comprises two steps. As previouslyindicated, the first step is to load the projector by withdrawing filmfrom the supply reel and inserting the film into slot 15 and guiding thefilm over guide rolls 18 and 21.

The second step is to move lever 16 from its righthand stop position 17ato its left-hand stop position 17b. This step requires a depression ofthe lever so that the same is clear of the recess at stop 17a. Suchdepression permits movement of the lever along slot 17 toward the leftand into the stop position 17b in which the lever is temporarilymanually held in its depressed position.

Depression of lever 16 while still in the position 17a causes a downwarddisplacement of plate to which the lever is fixed and thus also of stud77. This movement of the stud rotates film guide 53 from its closedposition into an open position in which it is retained when and whilethe lever is depressed. The depression of the lever also clears the sameof bar 45 so that plate 31 and all the components supported thereon canbe freely moved toward the left. Such movement of the plate 31 towardthe left effects the threading operation as will now be more fullyexplained.

As shown in FIG. 4, film 25 when inserted into slot 15 bears againstguide 50 on plate 31 and is thus carried along with the guide. As plate31 is moving toward the left, the loop-forming movement of bearing andshaping member 82 is initiated by stud 72 meeting cam 87 secured to baseplate 30. The stud slides along the camming surfaces of the cam, therebycausing a clockwise rotation of upper loop setting lever 43. Thisrotation causes nose 88 to cam upper loop setter 54 about its post 81thereby turning member 82 upwardly which, in turn, pulls film 25 fromthe supply reel thus forming the upper loop as indicated by an arrow inFIG. 5. Film 25 is now resting against upper sprocket 40 also mounted onplate 30, though not necessarily engaged with the teeth of the sprocket.

Lever 16 is now released and as a result it moves from the full lineposition shown in FIG. 5 into its dashdotted position in which it locksitself in the recess at the position 17b. The threading operation is nowcompleted as far as action by the operator is concerned.

Plate 70 moves upwardly when the lever is released and as a result stud72 releases lever 83. Loop setter 54 now drops down, aided by spring 75.Guide 53 is also released due to the upward movement of stud 72,together with plate 70 and moves into the position shown in FIG. 2. Theguide now returns into its closed position thereby urging the film intoengagement with the teeth of sprocket 40 as soon as the projector isstarted if the film did not engage the sprocket teeth before by theinitial action of the loop setter 54.

Upon completion of the movement of plate 31 toward the left film guide50 has reached its position coacting with stationary film guide 37, asis shown'in FIG. 5, so that the film is now held in the projection slotformed by guides 37 and 50.

The completed upper loop is clearly shown in FIG. 2.

The movement of plate 31 toward the left has also moved the focusingassembly 52 and the projector lens drum 51 into the position of FIG. 3so that the projection lens can be focused by pressing in knob 13 aspreviously described.

Describing now the operations which occur in the part of the mechanismbelow the optical center axis 300, reference is made to FIGS. 6 and 7.As shown in these figures, the film is trapped by guide 123a on thelower loop setter 57 and is taken along as plate 31 moves toward theleft. As a result the film is forced to wrap itself about capstan 93 bythe action of rollers 130 and 131 on filter rollers 58 and 59respectively. Rollers 130 and 131, and hence the filter rollers arespread apart while riding along the camming surfaces 101 and 102 ondouble cam plate 44 on base plate 30. When rollers 130 and 131 leave thedouble cam they move toward each other and into the position of FIG. 7.Moreover, the movement of rollers 58 and 59 toward the left togetherwith plate 31 forces the film into engagement with lower sprocket 41 asshown in FIG. 7.

The film is now so positioned that it can be transported in theconventional manner by the movements of claw 39 (see FIG. 6) when theprojector motor is started.

'Lower loop setter 57 which also has moved during the displacement ofplate 31 from the position of FIG. 6 into the position of FIG. 7,occupies the position shown in dash-dotted lines in FIG. 6 when andwhile projection proceeds in normal fashion. It may be mentioned in thisconnection that the distance between the projection slot formed by filmguides 37 and 50 and sound capstan 98 is selected to achievesynchronization between pictures and sound in a conventional manner.

As described before jack 106 continuously reciprocates during normaloperation of the projector due to the coaction between cam 111 androller 1115 on arm 104 to which the jack is pinned at post 109. Duringsuch movement, a bracket 106a on the jack will miss pin 124 on arm 122of loop setter 57, that is, the jack will idle.

Assuming now the projector is started or that for some reason such as afault in the film due to torn sprocket holes, the film is not smoothlytransported and thus the length of the film between the projection slotand sprocket 41 tightens, and that the film portion between theprojection gate and upper sprocket 40 becomes bunched causing anenlargement of the upper loop, the film portion adjacent to arm 122presses against the arm causing the same to turn in counterclockwisedirection. In such turned position, which is shown in FIG. 7 indash-dotted lines, bracket 106a on arm 106 becomes engaged with pin 124during its next reciprocating movement, thereby swinging arm 122 intothe full line position of FIG. 7. As a result of such movement, arm 122pulls film down from above the projection slot thereby restoring thelower loop and reducing the upper loop to its normal size. Moreover,loop setter S7 is released to return to its normal position, as shown inFIG. 6, thus freeing its pin 124 from engagement with bracket 106a ofjack 106.

Referring now to FIGS. 8 and 9, during normal running of the projectorbelt 155 rotates both sprockets 40 and 41 and also both reels 11 and 12,either forward or in reverse. To effect rewind, the projector motor isstopped and operating lever 16 (FIG. 1) is returned to its loadingposition at 17a and the film is lifted out of slot 15. Pin 159, movingjointly with plate 131 (see FIG. 9), swings crank 152 so that crank pin151b is detached from hole 1490 of clutch 149 and crank pin 151a engageshole 154a of clutch 154. As a result, upon restarting the projectormotor supply reel 11 instead of take-up wheel 12 is now driven by clutchand belt 158.

FIG. 10 shows an assembly including coacting cams, links and crankswhich are automatically activated to set both loops when the lower loopshortens for any reason, such as a slow-up of the film transport, causedfor instance by torn sprocket holes. The assembly of FIG. 10 is drivenby toothed belt 155.

More specifically, a belt gear 165, a cam 166 and a cam 167 are pinnedto a rotary shaft 168. The general location of the assembly of FIG. 10is indicated in FIG. 8 by dotted lines.

The teeth of gear 165 are engageable with belt 155. In the inactiveposition of the assembly the gear is out of driving engagement with beltdue to the omission of, say, four teeth. Moreover, a post 169 on gear isslightly held in a springy detent 170.

The assembly further comprises posts 171, 172 and 173, all mounted onplate 31 for movement in unison with the same so that the posts occupyin the operating or left position of plate 31 definite and stationarypositions with reference to sprocket shafts 142 and 112, both mounted onbase plate 30 and also relative to shaft 168 which is supported by plate31.

A crank arm 174 pinned to post 173 has on one arm a film guiding surface174a similar to surface 123 on arm 122 of loop setter 57 (see FIG. 5).The arm 174b of the crank mounts a cam follower 175 riding on cam 166. Aspring 176 biases the crank in counterclockwise direction.

Cam 167 on shaft 168 has riding thereon one arm of a two-arm link 177pinned at 177a to a link 177b pivoted to post 172. The other arm of link177 is hinged to loop shaping member 82a which, in turn, is pinned topost 171. A light spring 1770 restrains the linkage formed by links 177and 177b to prevent rattling thereof.

OPERATION OF THE ASSEMBLY OF FIG. 10

Assuming now that the film should tighten between sprockets 40 and 41due to faulty film, as previously described, the film will press againstcrank 174 which, in turn, will cause its cam follower 175 to exertpressure against cam 166. The resulting torque on cam 166 is sufficientto force post 169 out of engagement with detent 170 and turn the cam.The tooth 178 of gear 165 will now engage moving belt 155. As a result,cams 166 and 167 will continue to rotate. Such rotation forces crank 174into the dash-dotted position and will also cause upper loop shapingmember 820 to move from the full line position into the dash-dottedposition by the action of link 177. As a result, both the upper loop andthe lower loop are reset.

When gear 165 is turned through an angle such that pin 169 re-entersdetent 170, there is no longer pressure on cam follower 175.Accordingly, the crank 174 will return into its full line position aswill also loopshaping member 82a so that the entire assembly is nowreturned to its inactive position shown in FIG. in full lines.

FIGS. 11 and 12 show a modification of the loop setting assembly of thethreading mechanism which is highly sensitive in response duringoperation of the projector and also has more positive detent means thanthe loop-setting assemblies previously described.

The assembly comprises for control of the lower loop a roller 178mounted on a lever 179 pinned to a shaft 180 which, in turn, is pinnedto a lever 181. Shaft 180 is rotatable in a bearing housed in movableplate 31 and positions lever 181 to bear against a pin 182 on a wheel183 to rotate the same. Wheel 183 has in its peripheral wall twodiametrically opposite concave recesses 187 for a purpose which will bemore fully explained hereinafter, and coacts with the preferablyrubber-lined or otherwise cushioned periphery of an idler roll 184,swingably supported on a link 184a pivotal about a pin 1841: on plate31. The idler roll is engageable with a flange 185 on belt gear 156 butis normally held out of engagement with this flange by the action of aspring 188. As is shown in FIG. 8, the belt gear is seated on shaft 112also seating the lower sprocket gear 41.

Rotation of wheel 183 into an angular position in which a non-recessedportion of the peripheral wall of the wheel engages wheel 184, causes adepression of wheel 184 into driving engagement with flange 185 of gear156 which, in turn, is driven by belt 155, thereby establishing atransmission train between gear 156 and wheel 183.

When the projector is normally operating, the lower loop formed by film25 is about as indicated in full lines in FIG. 11 and lever 179 occupiesthe full line position into which it is biased by a spring 179a actingagainst a pin 179b. If now the film tightens due to torn sprocket holesas previously explained, the film presses against roller 178 on lever179 and turns the lever counterclockwise and depresses lever 181 againstpin 182. As a result, wheel 183 is turned from the angular position ofFIG. 11 in which one of its recesses 187 is in registry with theperipheral wall of idler roll 184 into and beyond the position of FIG.12 in which the non-recessed peripheral wall of wheel 183 engages theperiphery of roll 181 thereby pressing this roll downwardly against theaction of spring 188.

As a result, wheel 183 is now driven by gear 156 via the aforedescribedtransmission train until a second pin 186 on wheel 183 engages arm 181of lever 179 thereby turning the lever in clockwise direction and intothe dash-dotted position of FIG. 11. As a result, the film is pulleddown from the area above the projection slot and the lower loop isrestored by roller 178 as it is shown in dotted lines in FIG. 11.

As wheel 183 continues its rotation it releases arm 181 and thus roller178. When the wheel reaches the position in which its second recess 187re-engages idler roll 184, this roller is disengaged by spring 188 fromgear flange 185. The assembly now comes to a stop and lower loop setter178, 179, 181 returns into the full line position.

Referring to FIGS. 13 and 14, a novel means is shown for stopping a filmduring projection, manually or automatically. The frame at the selectedstopping point is in register with the optical system and isilluminated.

In the conventional part of the means, film 25 positioned in a planenormal to the drawing is engaged in a sprocket hole 25A by a claw 190dependent upon the position of an axial cam 191 in contact with a camfollower 192 mounted on a claw arm 193. Arm 193 is biased toward cam 191by a spring 194 on a shouldered pin 195 passing through the projectorframe. For transport of the film, the movement of arm 193 normal to thedrawing is obtained, by way of example, by a scotch yoke 196 functioningas a cam follower for a radial cam 197. As is evident, arm 193 must movein two planes. For this purpose, pin 195 is free to swivel as is abearing surface 193A on arm 193. A shutter 198 and cams 191 and 197 arepinned with a drive pulley 199 to a shaft 200 which is journaled inbearings 201 and 202. This completes the description of the prior artfor clarity of the following.

Bearings 201 and 202 allow axial movement of shaft 200 under theinfluence of a solenoid 203 acting through a crank, arm 204 to move theshaft against a spring 205.

Also pinned to shaft 200 is a cam 206 operating an electrical switch207, a plate 208A having a groove 209A and a friction disc 210A.

Slidable and rotatable on shaft 200 is a sleeve 221 which has pinned toit a worm gear 212, a cam 213 operating anelectrical switch 214, a plate2088 having a tongue 2098 and a friction disc 210B. Axial movement ofsleeve 211 is adjustable and limited by the positioning of a fork 215between a cam 213 and a plate 2088. The fork is mounted on a lengthwiseadjustable bracket 215A. A worm gear 212 is engaged by a worm wheel 216on a shaft 217 which should be visualized as being connected to a beltbetween upper and lower sprockets 40 and 41 respectively. It is to benoted that these sprockets, in this illustration, are not connected bybelt to the motor drive 140.

Inspection of the mechanics will show that the motor belt driving pulley199 will cause operation of the film transport, switches 207 and 214,the upper and lower sprockets and both reels 11 and 12, but onenergizing solenoid 203 the pulley will not operate the sprockets andreels due to the resulting displacement of shaft 200. Also, onenergizing, claw will move from an operating range X to a non-operatingrange Y and switch 214 will cease operating. The assembly on sleeve 211,having practically no flywheel momentum, will act as a fast brake (dueto the total friction in the belt drive bearings etc.) when groove 209Aleaves tongue 209B and friction discs 210A, 2108 separate. This brakemakes it possible to have a small tolerance in the variation of timelapse between energizing and claw withdrawal. On de-energizing solenoid203 spring 205 moves the shaft toward the left whereby disc 210A firstcontacts disc 210B lightly to get sleeve 211 started. Sleeve 208A willthen slip around until groove 209A engages tongue 209B. Infrequently,when tongue and groove match on deenergizing, sleeve 211 will be startedabruptly.

Finally, it is noted that cams 213, 206, 191 and 197 operate in a fixedradial angularity when solenoid 203 is de-energized.

In order to see the film frame in register, the claw must be withdrawnto area Y" during its retrace normail to the drawing. To this end,referring to FIG. 15, an electrical circuit employing a relay 218,having contacts 219 and 220 is used in cooperation with cam 213. Cam 213shows a raised sector which closes contact 214 during the claw retrace.Closing a push button switch 260 to a source 261 will energize relay 218at the instant of claw retrace. Contact 220 will then energize solenoid203 and claw arm 193 will move into area Y. Contact 219 seals in relay218 so that the solenoid energization is independent of the position ofcam 213 when it is stopped.

When it is desired, manually or automatically to restart the film, thecircuit at switch 260 is opened. However, without cam 206 (that is withcontact 207 shorted) the returning claw may engage the film at any pointin its forward traverse and thus upon missing the sprocket hole woulddrag the film and shorten the upper loop. To avoid such action, cam 206shows a dwell area during the claw retrace to ensure deenergizationduring this time independent of the opening of switch 260.

Switch 260 may be a time delay switch or a delay net work settable forselected stop and release periods to control the stoppage of a selectedframe in the picture gate. The use of such automatic variable timingnetworks, which are well known in the art, makes projectors equippedwith the mechanism and circuitry of FIGS. 13,- 14 and 15 suitable foruse as stop motion projectors or motion analyzers.

Referring now to FIG. 16, this figure shows an assembly by means ofwhich film 25 can be quickly and automatically rewound on supply reel11. Such fast rewind is effected by performing the following steps:

a. Lever 16 (FIG. 1) is moved into the position in I which plate 31 isin the loading position.

b. Film 25 is lifted out of slot 15.

c. Motor is put in reverse mode.

An electric interlock permits normal speed in forward or reverse butprevents fast rewind unless step (a) is first carried out as will bedescribed in connection with FIG. 17.

Supply or storage reel 11 is fixed at one end ofa shaft 301 by aconventional reel holder and lock 302. If reel 11 is mounted on an armsuch as is shown in FIG. 1, lock 302 may be visualized as a belt gearand belt assembly driving another gear on the arm.

A belt gear 303 is pinned to other end of shaft 301 and a ratchet 304 ispinned to the shaft close to reel 11. Spindled on shaft 301, an elongatehub 305 has pinned to it on one end a disc 306 by means ofa collar 307and at the other end of the hub a collar 308 is pinned. Between thecollars, hub 305 presents a smooth bearing surface carrying thefollowing freely rotatable members: a spring 309, a disc 310, a beltgear 311, another disc 312 and a thrust bearing 313. Disc 310, gear 311and disc 312 are friction members in that one side of disc 310 is infrictional contact with two buttons 314 on one side of gear 311 and oneside ofdisc 312 is in frictional contact with two buttons 315 on theopposite side of gear 311, the degree of frictional drag beingcontrolled by the choice of spring 309. For clarity in the figure, thediscs 310, 312 and gear 311 are shown out of engagement. Further, therim of the disc 312 is frictionally engaged by a pressure pad 316 on aspringy arm 317. The thrust of spring 309 terminates on one end atcollar 307 on disc 306 and on the other end at collar 308.

Disc 312 carries a pin 318 which passes through a slot 319 to cooperatewith a pawl 320 spindled on a pin 321 fixed in disc 306. A spring 322biases pawl 320 into engagement with ratchet 304. Pawl 320 has a camsurface 323 such that the relative position of discs 312 and 306determines the engagement of the pawl with ratchet 304. In the figure,the pawl is shown to be disengaged. Thus, upon opposite displacement ofdiscs 312 and 306 into an angular position in which pin 318 is at thefar end of the slot 319, pawl 320 will engage the ratchet. Spring 321 isvery soft compared to the frictional torque at pad 316, that is, thetorque of pad 316 is larger than frictional torque of the two pads 315.Gear 311 is engaged by toothed belt which, besides driving the filmtransport sprockets and the shutter, passes around a belt gear 324rotating jointly with a spur gear 325.

An arm 326 spindled on a post 327 carries at its free end a shaft 328which spindles a belt gear 329 rotating with a spur gear 330. Arm 326swings gear 330 into or out of engagement with gear 325 as indicated byan arrow at the axis of shaft 328. A toothed belt 331 connects beltgears 329 and 303.

Another arm 332 spindled at pin'333 has two pins 334, 335 straddling arm326. Thus, clockwise movement of arm 332 causes gear 330 to engage gear325. At the lower end of arm 332, a pin 336 extends through a slot 337in base plate 30 to cooperate with a bar 338 attached to movable plate31. Movement of plate 31 into the loading position (as shown) causes pin334 to swing gear 330 into engagement with gear 325 and converselymovement of plate 31 into the operational position causes pin 335 toswing thegear 330 out of engagement with gear 325. Arm 332 is biasedcounter= clockwise by a spring 339.

OPERATION OF THE FAST REWIND ASSEMBLY In normal forward operation, plate31 is in the operational position and belt 155 is driven in thedirection indicated by an arrow 340. Accordingly, disc 311 rotatingcounter-clockwise, frictionally turns disc 312 which, in turn, isretarded by friction pad 316. This causes pin 318 to bear against thenear wall of slot 319 in disc 306 which is being rotated by frictionbuttons 314, disc 310, spring 309, collar 308 and hub 305. At thisposition of pin 318 in slot 319, the pin cams pawl 323 out of ratchet304. Since plate 31 is in the operational position, shaft 301 is freeand film 25 is pulled off reel 11 as demanded by the sprocket drive. Inother words, the assembly supported on hub 305 is freewheeling on shaft301.

In normal reverse operation, belt 155 is driven in the directionopposite to arrow 340 and plate 31 is retained in the operationalposition. Accordingly, gear 311 is driven clockwise and pin 308 is thusmoved to the far end of slot 319 so that pawl 320 is now in engagementwith ratchet 304. Hence, the assembly supported on hub 305 rotates withshaft 301 and film is rewound on supply reel 11. The gradually wideninggap of the differential speed between the film drive and the reel drivedue to the gradually increasing circumference of the film rewound uponthe reel 11 causes slippage of friction buttons 315 relative to disc312. Spring 309 abutting against collar 308 now supplies the pressurenecessary to pull film onto reel 11 without damaging the sprocket holesof the film.

To effect fast rewind, the projector motor must be stopped and plate 31be moved into its loading position. FIG. 16 shows condition of theassembly when the projector motor is stopped in normal forward operationand plate 31 is moved into the loading position but before the motor isstarted in reverse.

When now the motor is started, belt 155 again turns disc 311 clockwise,that is, in opposition to arrow 340. Drag of friction pad 316 on disc312 now causes pin 318 to move to the rear of slot 316 and pawl 320therefore engages ratchet 304. Gear 330 has been .moved into engagementwith gear 325 by the displacement of plate 31 and the resulting pivotingof arm 332 as previously described. Gear 325 now drives gear 330 at astepped-up speed due to the ratio between the gears. Gear 330, in turn,through large gear 329, belt 331 and smaller gear 303 drives shaft 301at a yet higher speed. Thus, ratchet 304 over-runs pawl 320 as both turnclockwise during fast rewind, the ratchet teeth merely clicking past thepawl. Hence, the film is rewound with a speed determined by the gearratio.

Suitable circuitry for the electric interlock referred to in connectionwith the description of FIG. 16 is shown in FlG. 17. This figure showsan electric safety control which prevents operation of the motor inforward drive when movable plate 31 is in the loading position.

As shown, plate 31 in the loading position closes a switch 239 and opensa switch 240 which, in turn, opens the forward energizing circuit forthe motor through a control switch 237 thereby rendering inoperative theforward position of the control switch but permitting the closing of theenergizing circuit for reverse drive of the motor via switch 239. Whenplate 31 is placed in the operational or running position a switch 238and switch 240 are closed but switch 239 is open so that the motor canbe started for forward drive.

Switches 239 and 238 are arranged to be opened when and while plate 31is between its loading position and its operational position to preventoperation of the film drive sprockets as such operation may damage thefilm. When plate 31 has reached either the loading position or theoperational position, switches 239 and 238 are closed.

What is claimed is:

1. In a motion picture film projector, a film-threading mechanismcomprising in combination:

a casing including in one of its outer walls a continuous slot;

21 baseplate stationarily mounted in the casing parallel to and behindsaid slotted wall;

a front film guide including a film gate mounted on the base plate onone side of the slot adjacent to part of the length thereof;

an upper and lower sprocket rotatably mounted on the baseplate anddisposed on the opposite side of said slot;

a movable plate displaceable within the casing disposed between saidplate and said wall parallel thereto;

a rear film guide including a film gate, film-threading means andloop-setting means mounted on the movable plate,

said movable plate being displaceable on the opposite side of the slotbetween a loading position for inserting into the slot a length of thefilm to be threaded and an operating position in which said film guidesdefine therebetween a projection slot and said threading means andloop-setting means coact with the sprockets and film in the slot tothread the film upon the sprockets and to form an upper and a lower loopin the length of the film between the two sprockets;

an assembly for stopping transport of the film at a selected frame, saidstop assembly including:

film transport means for transporting film threaded upon said sprockets,said transport means being movable into and out of transport engagementwith the film;

a rotatable control shaft slidable into either one of two axialpositions;

a solenoid means coacting with said shaft to control the axial positionthereof in accordance with the state of energization of the solenoidmeans;

transmission means on the shaft releasably coupled to the sprockets forrotating the same;

a driving means for rotating the sprocket transmission means, saiddriving means being coupled to the shaft in one axial position thereofand being uncoupled from the shaft in the other axial position thereof,and for driving the film transport means in either axial position of theshaft;

clutch means for coupling the sprocket transmission means to the shaft,said clutch means coupling the transmission means in said one axialposition and uncoupling said transmission means in said other axialposition of the shaft;

film transport control means moving the transport means into engagementwith the film in said one axial position of the shaft and moving thetransport means out of such engagement in said other axial position;

control circuit menas including switches controlling an energizationcircuit for the solenoid means and cam means on the shaft controllingsaid switches in accordance with the angular position of the shaft,operation of said control circuit means activating said solenoid meansto displace the shaft from said one axial position to said other axialposition thereby moving the film transport means out of engagement withthe film and uncoupling the clutch means thus stopping driving of thesprockets via the sprocket transmission means; and

a rewind assembly, said assembly including:

a supply reel for the film to be threaded and a take-up reel;

drive means for winding the film from one reel upon the other;

first transmission means drivable by the drive means for forward windingof the film from the supply reel upon the take-up reel;

second transmission means drivable by the drive means for reversewinding of the film from the take-up reel upon the supply reel;

clutch means having a first clutching position coupling said firsttransmission means to the drive means and a second clutching positioncoupling said second transmission means to the drive means; and

clutch actuating means coacting with the clutch means for selectivelymoving the same into either one of said clutching positions, saidactuating means being coupled with said movable plate for control by theposition thereof, placement of the movable plate in the operationalposition operating the actuating means for moving the clutch means intothe first clutch position to effect forward drive of the film andplacement of the movable plate in the loading position operating theactuating means for moving the clutch means into the second clutchingposition to effect rewind of the film.

2. In a motion picture film projector, a film-threading mechanismcomprising in combination:

a casing including in one of its outer walls a continuous slot;

a baseplate stationarily mounted in the casing parallel to and behindsaid slotted wall;

a front film guide including a film gate mounted on the base plate onone side of the slot adjacent to part of the length thereof;

an upper and lower sprocket rotatably mounted on the baseplate anddisposed on the opposite side of said slot;

a movable plate displaceable within the casing disposed between saidplate and said wall parallel thereto;

a rear film guide including a film gate, film-threading means andloop-setting means mounted on the movable plate;

said movable plate being displaceable on the opposite side of the slotbetween a loading position for inserting into the slot a length of thefilm to be threaded and an operating position in which said film guidesdefine therebetween a projection slot and said threading means andloop-setting means coact with the sprockets and film in the slot tothread the film upon the sprockets and to form an upper and a lower loopin the length of the film between the two sprockets;

an assembly for stopping transport of the film at a selected frame, saidstop assembly including:

film transport means for transporting film threaded upon said sprockets,said transport means being movable into and out of transport engagementwith the film;

a rotatable control shaft slidable into either one of two axialpositions;

a solenoid means coacting with said shaft to control the axial positionthereof in accordance with the state of energization of the solenoidmeans;

transmission means on the shaft releasably coupled to the sprockets forrotating the same;

a driving means for rotating the sprocket transmission means, saiddriving means being coupled to the shaft in one axial position thereofand being unloaded from the shaft in the other axial position thereof,and for driving the film transport means in either axial position of theshaft;

clutch means for coupling the sprocket transmission means to the shaft,said clutch means coupling the transmission means in said one axialposition and uncoupling said transmission means in said other axialposition of the shaft;

film transport control means moving the transport means into engagementwith the film in said one axial position of the shaft and moving thetransport means out of such engagement in said other axial position;

control circuit means including switches controlling an energizationcircuit for the solenoid means and cam means on the shaft controllingsaid switches in accordance with the angular position of the shaft,operation of said control circuit means activating said solenoid meansto displace the shaft from said one axial position to said other axialposition thereby moving the film transport means out of engagement withthe film and uncoupling the clutch means thus stopping driving of thesprockets via the sprocket transmission means; and

a film rewind mechanism, said mechanism comprising:

a film supply reel and a film take-up reel;

reversible power drive means operable for forward and rewind of the filmrespectively;

a normal speed rewind assembly including first transmission meansconnected to the supply reel, and first coupling means for coupling saidtransmission means to the drive means, said coupling means being biasedinto disengagement and movable into engagement by placing the movableplate in its operational position and activating the drive means forrewind; and

a fast rewind assembly including second transmission means having ahigher transmission ratio than the first transmission means alsoconnected to the supply reel, and second coupling means for couplingsaid second transmission means to the drive means, said second couplingmeans being biased into disengagement and movable into engagement byplacing the movable plate in its loading position and activating thedrive means for rewind.

3. The projector according to claim 2 wherein said power drive meanscomprises a rotatable shaft seating the supply reel for rotation inunison therewith, said first and second transmission means idling on theshaft when the power drive means are activated for forward drive, andwherein said first transmission means comprise one-way coupling meansfor coupling the first transmission means to the shaft, said couplingmeans being biased into disengagement during forward drive and includingfrictional coupling elements causing movement of the one-way couplinginto driving engagement with the shaft in response to activating saiddrive means for rewind and moving the movable plate in its operationalposition thereby driving the supply reel for normal speed rewind.

4. The projector according to claim 3 wherein said second transmissionmeans are coupled to the shaft and comprise several coactingtransmission members, one of said members being movable into and out ofcoacting relationship with the other members thereby rendering thetransmission means inactive, and wherein the second coupling means coactwith said movable transmission member for moving the same into and outof said relationship and are controlled by the position of the movableplate, movement of said plate into its loading position operating saidsecond coupling means to move the movable transmission member into itsposition coacting with the other transmission members thereby activatingthe second transmission means.

5. The projector according to claim 4 wherein said one-way couplingmeans is a pawl-and-ratchet means the ratchet and the pawl of said meansbeing rotated at a differential speed and in the same direction by the

1. In a motion picture film projector, a film-threading mechanismcomprising in combination: a casing including in one of its outer wallsa continuous slot; a baseplate stationarily mounted in the casingparallel to and behind said slotted wall; a front film guide including afilm gate mounted on the base plate on one side of the slot adjacent topart of the length thereof; an upper and lower sprocket rotatablymounted on the baseplate and disposed on the opposite side of said slot;a movable plate displaceable within the casing disposed between saidplate and said wall parallel thereto; a rear film guide including a filmgate, film-threading means and loop-setting means mounted on the movableplate, said movable plate being displaceable on the opposite side of theslot between a loading position for inserting into the slot a length ofthe film to be threaded and an operating position in which said filmguides define therebetween a projection slot and said threading meansand loop-setting means coact with the sprockets and film in the slot tothread the film upon the sprockets and to form an upper and a lower loopin the length of the film between the two sprockets; an assembly forstopping transport of the film at a selected frame, said stop assemblyincluding: film transport means for transporting film threaded upon saidsprockets, said transport means being movable into and out of transportengagement with the film; a rotatable control shaft slidable into eitherone of two axial positions; a solenoid means coacting with said shaft tocontrol the axial position thereof in accordance with the state ofenergization of the solenoid means; transmission means on the shaftreleasably coupled to the sprockets for rotating the same; a drivingmeans for rotating the sprocket transmission means, said driving meansbeing coupled to the shaft in one axial position thereof and beinguncoupled from the shaft in the other axial position thereof, and fordriving the film transport means in either axial position of the shaft;clutch means for coupling the sprocket transmission means to the shaft,said clutch means coupling the transmission means in said one axialposition and uncoupling said transmission means in said other axialposition of the shaft; film transport control means moving the transportmeans into engagement with the film in said one axial position of theshaft and moving the transport means out of such engagement in saidother axial position; control circuit menas including switchescontrolling an energization circuit for the solenoid means and cam meanson the shaft controlling said switches in accordanCe with the angularposition of the shaft, operation of said control circuit meansactivating said solenoid means to displace the shaft from said one axialposition to said other axial position thereby moving the film transportmeans out of engagement with the film and uncoupling the clutch meansthus stopping driving of the sprockets via the sprocket transmissionmeans; and a rewind assembly, said assembly including: a supply reel forthe film to be threaded and a take-up reel; drive means for winding thefilm from one reel upon the other; first transmission means drivable bythe drive means for forward winding of the film from the supply reelupon the take-up reel; second transmission means drivable by the drivemeans for reverse winding of the film from the take-up reel upon thesupply reel; clutch means having a first clutching position couplingsaid first transmission means to the drive means and a second clutchingposition coupling said second transmission means to the drive means; andclutch actuating means coacting with the clutch means for selectivelymoving the same into either one of said clutching positions, saidactuating means being coupled with said movable plate for control by theposition thereof, placement of the movable plate in the operationalposition operating the actuating means for moving the clutch means intothe first clutching position to effect forward drive of the film andplacement of the movable plate in the loading position operating theactuating means for moving the clutch means into the second clutchingposition to effect rewind of the film.
 2. In a motion picture filmprojector, a film-threading mechanism comprising in combination: acasing including in one of its outer walls a continuous slot; abaseplate stationarily mounted in the casing parallel to and behind saidslotted wall; a front film guide including a film gate mounted on thebase plate on one side of the slot adjacent to part of the lengththereof; an upper and lower sprocket rotatably mounted on the baseplateand disposed on the opposite side of said slot; a movable platedisplaceable within the casing disposed between said plate and said wallparallel thereto; a rear film guide including a film gate,film-threading means and loop-setting means mounted on the movableplate; said movable plate being displaceable on the opposite side of theslot between a loading position for inserting into the slot a length ofthe film to be threaded and an operating position in which said filmguides define therebetween a projection slot and said threading meansand loop-setting means coact with the sprockets and film in the slot tothread the film upon the sprockets and to form an upper and a lower loopin the length of the film between the two sprockets; an assembly forstopping transport of the film at a selected frame, said stop assemblyincluding: film transport means for transporting film threaded upon saidsprockets, said transport means being movable into and out of transportengagement with the film; a rotatable control shaft slidable into eitherone of two axial positions; a solenoid means coacting with said shaft tocontrol the axial position thereof in accordance with the state ofenergization of the solenoid means; transmission means on the shaftreleasably coupled to the sprockets for rotating the same; a drivingmeans for rotating the sprocket transmission means, said driving meansbeing coupled to the shaft in one axial position thereof and beinguncoupled from the shaft in the other axial position thereof, and fordriving the film transport means in either axial position of the shaft;clutch means for coupling the sprocket transmission means to the shaft,said clutch means coupling the transmission means in said one axialposition and uncoupling said transmission means in said other axialposition of the shaft; film transport control means moving the transportmeans into engagement with the film in said one axial position of theshaft and moving the transport means out of such engagement in saidother axial position; control circuit means including switchescontrolling an energization circuit for the solenoid means and cam meanson the shaft controlling said switches in accordance with the angularposition of the shaft, operation of said control circuit meansactivating said solenoid means to displace the shaft from said one axialposition to said other axial position thereby moving the film transportmeans out of engagement with the film and uncoupling the clutch meansthus stopping driving of the sprockets via the sprocket transmissionmeans; and a film rewind mechanism, said mechanism comprising: a filmsupply reel and a film take-up reel; reversible power drive meansoperable for forward and rewind of the film respectively; a normal speedrewind assembly including first transmission means connected to thesupply reel, and first coupling means for coupling said transmissionmeans to the drive means, said coupling means being biased intodisengagement and movable into engagement by placing the movable platein its operational position and activating the drive means for rewind;and a fast rewind assembly including second transmission means having ahigher transmission ratio than the first transmission means alsoconnected to the supply reel, and second coupling means for couplingsaid second transmission means to the drive means, said second couplingmeans being biased into disengagement and movable into engagement byplacing the movable plate in its loading position and activating thedrive means for rewind.
 3. The projector according to claim 2 whereinsaid power drive means comprises a rotatable shaft seating the supplyreel for rotation in unison therewith, said first and secondtransmission means idling on the shaft when the power drive means areactivated for forward drive, and wherein said first transmission meanscomprise one-way coupling means for coupling the first transmissionmeans to the shaft, said coupling means being biased into disengagementduring forward drive and including frictional coupling elements causingmovement of the one-way coupling into driving engagement with the shaftin response to activating said drive means for rewind and moving themovable plate in its operational position thereby driving the supplyreel for normal speed rewind.
 4. The projector according to claim 3wherein said second transmission means are coupled to the shaft andcomprise several coacting transmission members, one of said membersbeing movable into and out of coacting relationship with the othermembers thereby rendering the transmission means inactive, and whereinthe second coupling means coact with said movable transmission memberfor moving the same into and out of said relationship and are controlledby the position of the movable plate, movement of said plate into itsloading position operating said second coupling means to move themovable transmission member into its position coacting with the othertransmission members thereby activating the second transmission means.5. The projector according to claim 4 wherein said one-way couplingmeans is a pawl-and-ratchet means the ratchet and the pawl of said meansbeing rotated at a differential speed and in the same direction by theshaft when the second transmission means are activated for rotating theshaft thereby causing the pawl to slip on the ratchet and thus toover-run the one-way coupling means.